Low-Power-Consumption Fiber-Optic Anemometer Based on Long-Period Grating With SWCNT Coating

We report a low-power-consumption fiber-optic “hot wire” anemometer based on long-period grating (LPG) with single-wall carbon nanotubes (SWCNTs) coating. A uniform SWCNT film is deposited on a bare LPG acting as both light coupling and sensing element. By carefully selecting the order of the cladding mode and operating wavelength, the LPG shows a much higher temperature sensitivity than that of a regular fiber Bragg grating. Besides, SWCNT is a single-wall cylindrical nanostructure material with excellent absorption in the infrared range and high-thermal conductivity. Due to these two features, the proposed sensor has extremely low-power consumption and simple operation by utilizing a broadband light source as both heating source and probing light source. A sensitivity of 102.5 pm/(m/s) at the wind speed of 1 m/s was obtained experimentally with 1.6-
$\mu \text{m}$
-thick SWCNT film.